When comparing Li3 vs Joomla!, the Slant community recommends Li3 for most people. In the question“What are the best PHP frameworks?” Li3 is ranked 10th while Joomla! is ranked 19th. The most important reason people chose Li3 is:
Lithium has unified the relational and non-relational database APIs into a single one. Being one of the few frameworks to do it.
Specs
Ranked in these QuestionsQuestion Ranking
Pros
Pro Unified relational and non-relational database API
Lithium has unified the relational and non-relational database APIs into a single one. Being one of the few frameworks to do it.
Pro Robust plugin architecture
Lithium makes use of PHP namespaces to create a powerful plugin architecture. Almost every component of the framework is replaceable.
Pro Fast Bootstrap & Autoloader
This framework loads faster than most due to its class autoloader. It is flexible as well and handles older classes - but requires the developer to define transforms here for naming convention, includes, etc. Many other frameworks use Composer for autoloading and that significantly slows down their bootstrap time because Composer's autoloader is extremely compatible without much developer interaction (it does not require as much involvement for autoloading legacy libraries). So it's a trade-off, speed vs. a little bit of up-front work.
Pro Integrated unit testing
Lithium comes with integrated unit testing. It also has a test dashboard.
Pro Aspect inspired filter system
Lithium's filter system is based on the paradigm of Aspect-oriented programming which aims to increase modularity by separating cross-cutting concerns and helping speed up development.
Pro Great for building an API
Lithium can return JSON and many other formats from the same actions that render templates increasing productivity in many cases. It handles a "type" key in the route which allows it to render various responses with different Content-Types. This is incredibly useful and easy to extend. This combined with closures in routes makes Lithium a very good framework for building a RESTful API.
Pro Highly customizable templates
Joomla allows for heavily customizable templates to be changed from the admin interface without needing to hack.
Pro Powerful and user-friendly admin interface
Admin interface is constantly being iterated on to remove unnecessary legacy features and to streamline the interface. Resulting in a very clean and easy to understand interface that also offers a wide range of options.
Pro More than 8000 extensions
Which can be found here.
Pro Easy to pick up
Pro Great for social networking and commerce sites
Joomla has both a good native support and a great list of extensions that make creating either a social networking or a commerce site easy.
Cons
Con Less than ideal documentation
Documentation is scattered so it takes a little while to learn and figure some things out.
Con Insecure
It's common-place for a Joomla-based website to be defaced, often very quickly. This is most often due to the low quality of extensions.
Con Extensions are scarce, badly maintained & rarely good
If it's not part of the default Joomla installation, quality extensions are rare. Joomla has a extensions library, but it is full of abandoned, dated or bloated components, modules and plugins.